This invention relates to current-switched Josephson junction logic and memory circuits.
Logic and memory applications of Josephson tunnel junctions have received considerable attention in recent years. Many designs employ the influence of magnetic fields upon the current-voltage (I-V) characteristics. For gates comprising single junctions or two or more junctions in parallel (interferometers), an applied magnetic field reduces I.sub.J, the maximum current that the gate can carry in the V=0 state. The reduction of I.sub.J below the bias current I.sub.b causes the gate to switch from V=0 to a finite voltage, causing I.sub.b to be largely diverted to parallel resistive or inductive paths where it acts as a control or bias current for other gates.
An alternative means for inducing switching from V=0 to V.noteq.0 is current-switching, the direct addition of part of the control current to the bias current, with switching occurring if the sum exceeds a fixed I.sub.J. A design called the "goalpost" using this approach is described in my U.S. Pat. No. 4,051,393.